Light‐Driven Ratchet Mechanism Accelerates Regioselective Metal‐Cation Exchange in a Heterobimetallic Helicate

Abstract

Abstract Molecular machines rely on their capacity to exploit non‐equilibrium processes to perform work. However, the development of these non‐equilibrium processes, such as molecular ratchets, is still in its early stages. Here, we report a diazocine‐containing ligand ( L ) harbouring two distinct chelating coordination sites that can self‐sort into dinuclear homo‐ and heterobimetallic helicates ([Fe II 2 L ](OTf) 4 , [Co II 2 L ](OTf) 4 , [Zn II 2 L ](OTf) 4 , [Zn II Fe II L ](OTf) 4 , [Zn II Co II L ](OTf) 4 ) with precisely controlled metal cation distribution. The photoisomerisation of the helicates operates via a molecular ratchet mechanism, resulting in metastable diastereomers that shift the system from thermodynamic equilibrium. Continuous white‐light irradiation autonomously drives this ratchet process, selectively enriching an out‐of‐equilibrium pseudo‐mesocate structure. Crucially, the ratchet mechanism can significantly accelerate metal‐cation exchange from the [Zn II 2 L ](OTf) 4 helicate to the [Zn II Fe II L ](OTf) 4 helicate. Thus, the system operates in a manner reminiscent of a “claw machine”, selectively seizing Fe II ions when subjected to a precisely controllable external stimulus. These findings lay the foundation for creating adaptive and reconfigurable supramolecular structures that use non‐equilibrium phenomena on a molecular level.